Lung volume recruitment maneuvers and respiratory system mechanics in mechanically ventilated mice

Cannizzaro, Vincenzo; Berry, Luke J.; Nicholls, P.K.; Zosky, Graeme R.; Turner, Debra J.; Hantos, Zoltán; Sly, Peter D.

doi:10.1016/j.resp.2009.09.012

Cited by 16 publications

(15 citation statements)

References 37 publications

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“…A pressure of 30 cmH 2 O for each RM was necessary to maintain lung volume stable. In accordance with previous studies [4,5] RM with 25 cmH 2 O peak pressure were not sufficient to avoid a loss of lung volume (data not shown). The double sigmoidal nature of the murine pressure volume curve [38] may explain the positive response to RM with 30 cmH 2 O pressure.…”

Section: Discussionsupporting

confidence: 92%

“…Table 1 summarizes ventilation studies, in which either lung impedance was measured or ventilation was performed for at least four hours. The table reveals that many studies that have focused on lung mechanics examined only a relatively short period of ventilation [2][3][4][5] and only one study fulfilled both inclusion criteria [6]. Interestingly, studies in which mice were ventilated for more than three hours often provided cardiovascular parameters, but neglected the examination of lung functions [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…In mechanically ventilated mice the usefulness of RM with the specific aim to keep pulmonary compliance and other lung functions constant has been explored only sporadically. Previous RM studies in healthy mice have focused on short periods of ventilation and potential lung injury, but did not compare ventilation with and without RM over several hours [4,5]. In addition, the effect of RM on blood pressure in mice is not well defined, although increased intrathoracic pressure might decrease cardiac output [19].…”

Section: Introductionmentioning

confidence: 99%

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Recurrent Recruitment Manoeuvres Improve Lung Mechanics and Minimize Lung Injury during Mechanical Ventilation of Healthy Mice

2011

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IntroductionMechanical ventilation (MV) of mice is increasingly required in experimental studies, but the conditions that allow stable ventilation of mice over several hours have not yet been fully defined. In addition, most previous studies documented vital parameters and lung mechanics only incompletely. The aim of the present study was to establish experimental conditions that keep these parameters within their physiological range over a period of 6 h. For this purpose, we also examined the effects of frequent short recruitment manoeuvres (RM) in healthy mice.MethodsMice were ventilated at low tidal volume VT = 8 mL/kg or high tidal volume VT = 16 mL/kg and a positive end-expiratory pressure (PEEP) of 2 or 6 cmH2O. RM were performed every 5 min, 60 min or not at all. Lung mechanics were followed by the forced oscillation technique. Blood pressure (BP), electrocardiogram (ECG), heart frequency (HF), oxygen saturation and body temperature were monitored. Blood gases, neutrophil-recruitment, microvascular permeability and pro-inflammatory cytokines in bronchoalveolar lavage (BAL) and blood serum as well as histopathology of the lung were examined.ResultsMV with repetitive RM every 5 min resulted in stable respiratory mechanics. Ventilation without RM worsened lung mechanics due to alveolar collapse, leading to impaired gas exchange. HF and BP were affected by anaesthesia, but not by ventilation. Microvascular permeability was highest in atelectatic lungs, whereas neutrophil-recruitment and structural changes were strongest in lungs ventilated with high tidal volume. The cytokines IL-6 and KC, but neither TNF nor IP-10, were elevated in the BAL and serum of all ventilated mice and were reduced by recurrent RM. Lung mechanics, oxygenation and pulmonary inflammation were improved by increased PEEP.ConclusionsRecurrent RM maintain lung mechanics in their physiological range during low tidal volume ventilation of healthy mice by preventing atelectasis and reduce the development of pulmonary inflammation.

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Section: Discussionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Recurrent Recruitment Manoeuvres Improve Lung Mechanics and Minimize Lung Injury during Mechanical Ventilation of Healthy Mice

2011

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“…5-8). 6,12,20 Interestingly, Kloot et al 22 applied sequential recruitment maneuvers (30 s DI's separated by 30 s) in dogs and found that recruited volume decreased with each DI despite larger plateau pressures for the second and the third DIs, which might be explained by the existence of multiple steady states as exemplified by our model.…”

Section: Discussionmentioning

confidence: 58%

“…Investigators in the animal laboratory should also be aware of the potential for unpredictable states of derecruitment to be achieved by a recruitment maneuver, as DI are frequently used to standardize lung volume history prior to studies of lung function. 3,12 Finally, we must remember that any conclusions drawn from our model simulations rest on the assumptions made in constructing the model. Many of these assumptions were made in the interests of computational tractability, such as Poiseuille flow through each airway that was either fully open or completely closed.…”

Section: Discussionmentioning

confidence: 99%

Modeling the Complex Dynamics of Derecruitment in the Lung

Bates

2010

Ann Biomed Eng

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Recruitment maneuvers using deep inflations (DI) have long been used clinically with the objective of recruiting collapsed regions of the lung. Considerable uncertainty continues to exist, however, as to how best to employ recruitment maneuvers or even if they should be used routinely at all for patients receiving mechanical ventilation. Much of this uncertainty may arise from a lack of understanding about the dynamic nature of recruitment and derecruitment. To shed some light on this complex issue, we developed a time-dependent computational model of recruitment and derecruitment in the lung based on a symmetrically bifurcating airway tree in which each branch has a critical closing and opening pressure as well as pressure-dependent opening and closing speeds. Starting from the fully open state, the model underwent regular ventilation for 8 min followed by a series of identical DIs separated by 5 min of identical regular ventilation. We found that the geographical nature and extent of derecruitment before and 5 min after each DI were not always the same, demonstrating that the model exhibits multiple stable states. We conclude that the effectiveness of a recruitment maneuver is not only simply a function of the duration and magnitude of a DI, but may also have an unpredictable component arising from the distributed bi-stable nature of the derecruitment process itself.

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Relationship of respiratory mechanics parameters acquired by forced oscillation technique (FOT) and morphological measurements in BALB/c mice

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Lung volume recruitment maneuvers and respiratory system mechanics in mechanically ventilated mice

Cited by 16 publications

References 37 publications

Recurrent Recruitment Manoeuvres Improve Lung Mechanics and Minimize Lung Injury during Mechanical Ventilation of Healthy Mice

Recurrent Recruitment Manoeuvres Improve Lung Mechanics and Minimize Lung Injury during Mechanical Ventilation of Healthy Mice

Modeling the Complex Dynamics of Derecruitment in the Lung

Relationship of respiratory mechanics parameters acquired by forced oscillation technique (FOT) and morphological measurements in BALB/c mice

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